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# New Hemophilia B Gene Therapy Approved
- URL: https://www.fdaweb.com/new-hemophilia-b-gene-therapy-approved/
- Published: 2022-11-22T12:00:00.000Z
- Updated: 2026-09-14T18:07:18.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5153253

FDA has approved Behring’s Hemgenix (etranacogene dezaparvovec), an adeno-associated virus vector-based gene therapy to treat adults with Hemophilia B (congenital Factor IX deficiency) who currently use Factor IX prophylaxis therapy, or have current of historical life-threatening hemorrhage, or have repeated, serious spontaneous bleeding episodes. An agency [notice](https://www.fda.gov/news-events/press-announcements/fda-approves-first-gene-therapy-treat-adults-hemophilia-b?ref=fdaweb.com) says Hemgenix is a one-time gene therapy product given as a single dose by IV infusion. Its safety and effectiveness were evaluated in two studies of 57 adult men with severe or moderately severe Hemophilia B. Effectiveness was established based on decreases in the men’s annualized bleeding rate, FDA says.

The most common adverse reactions associated with Hemgenix included liver enzyme elevations, headache, mild infusion-related reactions, and flu-like symptoms. The notice says patients should be monitored for adverse infusion reactions and liver enzyme elevations in their blood.

The Behring application received priority review and orphan drug and breakthrough therapy designations.